1. Field of the Invention:
The present invention relates to a process for biochemically producing L-serine from 2-oxo-oxazolidine-4-carboxylic acid or a salt thereof (hereinafter abbreviated as OOC) in a high yield.
2. Discussion of the Background:
L-Serine is an amino acid found in proteins. It is important as a medical or foodstuff additive or as a raw material for cosmetics.
L-Serine is widely found in nature as a component for constructing proteins. L-serine has been heretofore produced by hydrolyzing silk yarn, flocks, sericin, human hair, swine hair, etc., which all contain relatively large amounts of L-serine. The liberated L-serine is separated from other amino acids and purified. However, the yield is low in this process. And the process is not necessarily advantageous or economical because of restrictions in the supply of raw materials, etc.
Some processes for the chemical synthesis of L-serine are also known. However, their product is the optically inactive DL form of serine. Separating L-serine from a DL mixture involves complicated optical resolution, etc. which cannot be said to be an industrially feasible process for the production of L-serine.
As a process for producing L-serine by fermentation, there is known a process for producing it from glycine by using microorganisms of the genus Pseudomonas, etc. However, this process is not advantageous from point of view of yield, economical considerations, etc.
On the other hand, as a process for producing L-serine utilizing enzymes, there exists a process which utilizes serine hydroxymethyl transferase derived from animals and microorganisms. However, this process suffers the disadvantage that expensive tetrahydrofolate must be incorporated, in addition to glycine and formaldehyde. Furthermore, the process is disadvantageous in that the yield is poor.
Thus there is a strongly felt need for a process which readily provides optically pure L-serine in high yields and in an economically advantageous manner.